Contrast media radiography

The increase in density in HUs or CT numbers is linearly dependent on the iodine concentration (mgl/mL) of the injected contrast medium. CT has two advantages over projection radiography. One is the significant increase in contrast resolution and sensitivity, which reduces the contrast detection threshold, thereby allowing a lower level of concentration of contrast media to be administered the other is the cross-sectional imaging, which permits successive visualization of structures without the superposition of other tissues to affect the image quality (632). 

Soluble barium salts are highly toxic and the use of barium sulfate as a contrast medium for radiography depends entirely on its highly insoluble nature as well as the density of the barium atom. 

The diagnosis of acute colonic obstruction is made by plain film radiography (Fig. 3.8a). An enema with water-soluble contrast medium and/or colonoscopy with biopsy are then performed to determine the... 

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